Brief Description Of The Prior Art
Concern for safety in the course of manufacturing and other industrial operations has heightened in recent years. Federal regulations have been promulgated and implemented which are intended to assure that there is occupational safety in the work place. Compliance with these dictates that certain specific actions shall be taken by management to assure that machines are safe to operate, and in general to be around, during the times the machines are in operation, or even when they are passive during maintenance or repair.
One such regulation requires that all electrical circuits connected to a specific machine or apparatus be turned "OFF" or interrupted, and positively locked out, at times when the machine or apparatus is being serviced or is being maintained. This assures that serious injuries or death resulting from the accidental engagement and operation of the machinery or apparatus at a time when it is thought to be inactivated will be avoided, and that precautions will be taken by management to see that safety precautions are taken in each instance to assure that the machines are positively inactivated.
In order to lock-out the power supply to machinery and apparatus at a time when the machinery is being serviced or maintained, a number of specific devices have been proposed, placed in use, and sometimes patented, for locking out switches of circuit breaker boxes at a time when these switches have been turned to the "OFF" position. This assures that there cannot be an inadvertent flipping "ON", or energization of, the circuit at these times. Formed wires or safety devices are presently offered by some electrical equipment manufacturers, and these devices can be used to lock-out/tag-out individual circuit breakers mounted inside high voltage panel boxes. Although these devices satisfy the literal requirements of the government regulations which apply, they are limited in their usefulness by certain practical considerations. For example, they are useful only in relatively large boxes containing a relatively few, widely spaced circuit breaker switches. More conventional, more widely used smaller boxes with numerous circuit breaker switches are not satisfactorily served by these devices.
Hein U.S. Pat. No. 2,978,613 describes a lock-out device for switch panels. An anchoring rod is attached to a switch panel adjacent the column of switches. Each switch has an aperture formed through the switch handle. A pair of arms is attached to the rod and one of these includes a locking pin which can be inserted into an aperture in a selected switch. The arm can then be pivoted in place to lock the switch out.
Another patent which addresses the problem of locking out a switch in a distribution panel is Leasher et. al. U.S. Pat. No. 4,006,324. This patent describes a switch lock means for switch actuators of an electrical distribution panel. The lock-out means is in the form of a bar secured to a front plate of an electrical distribution box and carrying an array of spaced bores. Locking elements are provided, and each one of them has one end which fits through a bore element in the circuit breaker, and an opposite end which fits into one end of the bore in the bar. A locking plate hinged at one end extends over and protects the bar.
U.S. Pat. No. 2,169,860 to Von Hoorn describes a guard for an electrical switch which includes a bar which extends between the side walls of guard members so as to engage and prevent movement of an operating switch lever.
A handle lock for locking a circuit breaker handle in either the "ON" or "OFF" position is disclosed in U.S. Pat. No. 2,937,248 to Michetti. The lock-out device of Michetti is a wire bent into a U-shaped configuration, with the free ends of the wire being bent inwardly toward each other. The circuit breaker handle is provided with a through hole or with recesses for reception of these opposite free ends of the U-shaped wire. When the wire is positioned with its free ends in the recess or through hole in the circuit breaker handle, the wire can be abutted against a backing element to prevent the handle from being pivoted from one position to the other.
Other devices for locking a circuit breaker switch in the "ON" position or the "OFF" position are shown in Pastene U.S. Pat. No. 3,109,899; Palmer U.S. Pat. No. 3,408,466; Dietz U.S. Pat. No. 3,629,529; Dimarco et. al. U.S. Pat. No. 4,300,030; Kobayashi et. al. U.S. Pat. No. 4,733,029 and Johnson et. al. U.S. Pat. No. 3,784,766.
Many of the foregoing devices are quite expensive in construction and some of them are bulky and heavy and difficult to place in operation. A need exists for an easily mounted, easily used and reliable switch lock-out or lock-on device which can be afforded and which assures a high degree of safety during its use.